Powered resectoscope

ABSTRACT

A cold-punch resectoscope is provided with a hydraulic actuator for automatically reciprocating the blade of the resectoscope within its sheath. A source of fluid pressure is connected to the hydraulic actuator and provided with a control means. A hydraulic circuit is connected between the control means and the hydraulic actuator for selective operation thereof.

United States Patent 1191 Dremann Oct. 9, 1973 1 POWERED RESECTOSQOPE 3,613,662 10/1971 Chrysostomides 128/311 x inventor: George Dremann, 1940 Hopkins 3,638,652 2/1972 Kelley 128/305 Berke ey Cahf 94707 Primary Exammer-Luc1e H. Laudenslager [22] Filed: Oct. 29, 1971 Att0rneyBruce & McCoy [21] Appl. No.2 193,658

[57] ABSTRACT 52 vs. (:1. 128/305, 128/7 A cold-punch rasectascopa is provided with a y 511 Int. Cl A6lb 17/32 lic actuator for automatically racipraaating the blade [58] Field of Search 128/305, 303, 31 1, of the resecmscope Within its Sheath- A Source of fluid 12 /7 pressure is connected to the hydraulic actuator and provided with a control means. A hydraulic circuit is [56] References Ci connected between the control means and the hydrau- UNITED STATES PATENTS lic actuator for selective operation thereof.

2,708,437 5/1955 Hutchins 128/7 10 Claims, 5 Drawing Figures (19 [2| I57 i l 1 I I 89 IO T 13 67 A e? A/QI 1 1 3 637 9 S65 1 91 7? 99 PAIENIEnmn slma T39 INVENTOR. GEORGE H. DREMANN BYE/bu; E M%\ 1 POWERED RESECTOSCOPE BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates to cold-punch transurethral resectoscopes, and more particularly to a means for powering the resectoscope to provide automatic continuous as well as single stroke controllable reciprocation of the cutting blade.

2. Description of the Prior Art The well-known Thompson cold-punch resectoscope was first described and used in I935. This resectoscope is considered by many doctors to be the preferred instrument for transurethral resection and to this day still maintains its basic form and its mode of operation as originally devised.

Generally, prostatic carcinomas are discoverd only after they have extended beyond the limits of the gland and are therefore not amenable to cure by total prostatectomy by one of the classical open surgical procedures. As a result, urinary obstructions associated with prostatic cancer must be dealt with by transurethral resection. The preferred form of resection of these urinary obstructions is accomplished manually by exerting a fulcrummed bending pressure on the external end of a Thompson cold-punch instrument. In this manner, the prostatic tissue is forced into the fenestra of the Thompson resectoscope where it can be resected by operation of the cutting blade.

The Thompson instrument is manually operated and requires considerable agility and dexterity of the user. In its present form, the manually operated resectoscope requires the use of both hands during transurethral surgery, one to hold the instrument and one to reciprocate the cutting blade. Since the resectoscope must be partially rotated during use to position the cutting blade, the ability of the user to manipulate the instrument is considerably restricted.

The actuator of the existing Thompson instrument is a thumb lever located in a fixed position on one sidethereof, and a user of the instrument is greatly restricted in his movements due to the variable positioning of the lever as a result of rotating the instrument during the resectioning operation. The restricted movement, together with the large number of manipulations required to complete the operation normally causes a high degree of fatigue in the user.

A different form of transurethral resection is provided by electrosection technique. In this technique, an electral cutting loop formed by an electrode is reciprocally mounted within a sheath. The electrical cutting loop actually burns the undesired portion of material away producing large amounts of heat together with the attendant disagreeable odor and associated shock. A further problem with this technique can occur if the obturator nerve is accidentally stimulated during a transurethral electroresection causing a sudden thigh movement. Although this occurs infrequently, it can cause the electric cutting loop to bite more deeply than desired. This in turn can possibly produce a catastrophic accidental perforation, resulting in severe shock, and even death. This type of perforation is virtually impossible when using the cold-punch technique because only a small discreet segment of tissue can be resected with a single stroke of the cutting knife. Likewise, no appreciable heat is generated in the surrounding tissues when the cold-punch technique is employed.

There therefore exists a need for a completely automatic cold-punch resectoscope which overcomes the above set forth disadvantages, and which may be utilized in one hand to thereby free the other hand of the user. The facility of use will help to further improve the user's surgical technique and allow him to more readily deal with any other problems that may arise during an operation.

The present invention produces the abovementioned results by means of a completely atuomatic, fluid operated, cold-punch transurethral resectoscope which allows a user to more easily and accurately sculpture the various prostatic sectors, and it is provided with built-in safety features whereby the resecting blade may be locked in position at either end of its stroke.

The present invention converts the present Thompson manually actuated two-handed resectoscope into a true single handed instrument of significantly greater flexibility and which frees a users other hand for supporting functions during the course of an operation.

SUMMARY OF THE INVENTION A hydraulic actuator for use with a cold-punch resectoscope having an elongated sheath which is formed for insertion in the transurethral tract. The actuator comprises an elongated assembly secured to the sheath and has a reciprocating piston mounted therein. The piston includes a hollow cylindrical rod extending from one end thereof which carries a resecting knife at the free end of the rod. The rod is disposed internally of the sheath. The assembly includes a pair of fluid inlet ports communicating internally of the assembly on opposite ends of the piston to enable it to be reciprocated. A manually controlled circuit is connected with the inlet ports for powered reciprocation of the piston and resecting knife in the sheath.

OBJECT OF THE INVENTION It is therfore an important object of the present invention to provide a resectoscope having a powered reciprocating blade contained therein.

Another object of the invention is to provide manually controlled powered resectoscope capable of being used with one hand.

A further object of the instant invention is to provide a resectoscope which requires fewer manipulations, smaller angular excursions, and shorter sheath insertions.

It is still another object of the invention to provide powered cold-punch resectoscope in which a single stroke or continuous reciprocating movement of the blade is controllable and adjustable.

It is still a further object of the present invention to provide a hydraulically operated resectoscope capable of being variably controlled by a foot pedal.

It is yet another object of the present invention to provide a powered reciprocating resectoscope with a portable hydraulic operating circuit capable of being placed in a portable carrying case.

And yet a further object of the present invention is the provision of a fluid operated resectoscope with a safety cutoff means-whereby the operating blade of the resectoscope may be locked at either end of its reciprocating movement.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent when the powered resectoscope disclose herein is considered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevation view of the carrying case for the hydraulic operating circuit of the present invention showing the manifold connection for the different elements;

FIG. 2 is a cross-section taken along the line 22 of FIG. 1;

FIG. 3 is a top plan view of the improved powered resectoscope of the present invention;

FIG. 4 is a side elevation of the foot pedal operator for the instant invention; and

FIG. 5 is a partial cross-sectional view of the operating cylinder of the powered resectoscope having means for rotation of the cutting blade.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there shown in FIGS. 1 and 2 is a preferred embodiment of a fluid operating circuit for use with the present invention. The circuit may take any number of forms, including a modular construction wherein individual modules are fastened together to form the complete operating circuit. The circuit is preferably held entirely within a carrying case 11, such as a briefcase, having upper and lower portions 13, 15. The upper portion 13 is formed as a lid hingely mounted on the lower portion 15, so as to be capable of being pivoted between the closed position shown in FIG. 1 and an open position at 180 thereto. A clasp 17 is provided at the front of the carrying case to hold or lock the upper and lower portions together, and if desired, may be provided with a lock of any suitable type, so as to prevent the unauthorized opening thereof.

Both the upper and lower portions are provided with insulating material 19 internally thereof, which completely surrounds the operating circuit in the closed position to muffle any noise caused by the operation of the circuit.

As shown more clearly in FIG. 2, the insulating material 19 is provided with a recessed area 21 housing the hydraulic operating circuit of the invention. A manifold assembly 23 is provided exteriorly of the lower portion 15, and has a plurality of conduits 24,25,26,27,30 extending into the recess 21 in the interior of the carrying case.

The outer end of conduit 27 is connected to a suitably filtered, regulated and lubricated fluid pressure source 28, such as an air compressor or the like. The inner end of this conduit is connected to the hydraulic operating circuit by a line 29 for feeding pressurized fluid into a multi-port distributor 31. The pressurized fluid is then simultaneously distributed, via lines 33,35, to a normally closed, manually operated, by-pass valve 37 and to the inner end of conduit 25. By-pass valve 37 includes a switch 39 mounted on the outside of the carrying case for operation of the by-pass valve, for reasons explained more clearly hereinafter.

Fluid passing through line 35 to conduit 30 is preferably connected to a control means such as a foot pedal operator 41 of the type shown more clearly in FIG. 4. This foot pedal contains a normally closed, manually operated, spring returned, two way valve 42 connected by a line, not shown, to a further conduit 25. Pressurized fluid passes from the valve 42 through conduit 25 to a line 43 contained within the carrying case.

Multi-port distributor 31 further distributes pressurized fluid, via line 45, to a normally opened, manually operated, spring returned, three-way valve 47 and into a direct acting, manually operated, four-way spool valve 49. The pressure of the fluid passing from distributor 3I into the hydraulic operating circuit will be the same throughout the circuit due to the simultaneous distribution thereof from the distributor.

With the hydraulic operating circuit containing pressurized fluid, any depression of the foot pedal operator 41 will open normally closed valve 42 to allow pressurized fluid to pass therethrough into line 43 and thus into a shuttle or double check valve 55. Fluid in valve 55 is fed to a normally opened, manually operated, spring return, three-way valve 57.

When valve 57 is in its normally opened position, fluid passes unrestricted therethrough to a pilot actuator 63 having a piston contained therein. The fluid pressure will move the piston against the action of a return spring to thereby contact and move a spool contained in the four-way valve 49 toward a further pilot actuator 65 contained on the other side of valve 49.

After the spool contained in four-way valve 49 has been completely shifted toward pilot actuator 65, the pressurized fluid contained in distributor 31 will pass through an internal passageway formed in four-way valve 49 to a line 67. Fluid flows unrestricted through a combination flow control and directional check valve 69 in the direction of a manifold 71 where it is simultaneously distributed to a pilot actuator 73 and to line 75. Fluid pressure from line 75 passes through conduits 24 to one of the lines 79 which may be connected so as to provide pressurized fluid to one side or the other of a cushioned piston actuator 78 mounted within the operating cylinder 80 of the resectoscope to thereby move the piston and a hollow rod 82 connected thereto. Rod 82 includes a cutting blade or resecting knife 83 attached to the free end of the rod. The knife is preferably the sharpened end of the hollow rod.

As shown in FIG. 5, the piston 78 is provided with tapered end or side portions to cushion the contact of the piston at either end of its stake. While the piston is reciprocating within the operating cylinder, 21 further piston contained within pilot actuator 73 is simultaneously moved toward three-way valve 57 against the action of, a spring biasing means. This movement of the piston held within the pilot actuator 73 closes three-way valve 57 thereby blocking the flow of fluid therethrough into pilot actuator 63. As this occurs, the fluid pressure acting against the depressed piston of the pilot actuator 63 is exhausted to atmosphere through a port (not shown) within the three-way valve 57.

During the operation of the circuit components, as described above, fluid will also be exhausted from the other end of the instrument cylinder containing piston 78 through one of the lines 77 into conduits 26 to a further line 81 in the carrying case. The exhausted fluid then enters a manifold 83 for simultaneous distribution through a combination flow control and directional check valve 85 and into a pilot actuator 87. Fluid passing through throttle control valve 85 then passes through a line 89 into a portion of the four-way valve 49 where it is exhausted to the atmosphere through a port (not shown). However, this flow of exhaust fluid to the atmosphere is restricted in its passage through throttle control valve 85, and a back pressure of sufficient magnitude is provided in line 81 to act against a piston contained in pilot actuator 87 and to move the piston downwardly thereby closing a normally opened three-way valve 91.

The speed of retraction or extension of the cutting rod can be separately controlled by adjusting the throttle control valves 69 and 85 to vary the back pressure on the piston 78.

The closing of valve 91 prevents fluid from passing from manifold 31 through line .45 to the three-way valve 47 for entry into valve 91 and thus into the pilot actuator 65. Upon exhaustion of the fluid from the circuit described above, the piston contained in pilot actuator 87 will be returned to its normal position by the action of a spring bias means contained therein. This will cause three-way valve 91 to be moved to its normally opened position to allow pressurized fluid to flow from manifold 31 through line 45, valve 47, valve 91 and I into the pilot actuator 65.

A further piston contained in pilot actuator 65 will be moved toward the four-way spool valve 49 thereby moving the spool of the four-way valve in the direction of pilot actuator 63. At the same time, flow of fluid through the spool valve 49 will be switched from line 67 to line 89. This will apply fluid pressure to the exhausted side of the instrument cylinder while at the same time allowing the pressurized side to be exhausted.

In this manner, it can be seen that fluid pressure can be alternately applied to and exhausted from both sides of piston 78 to automatically provide a single stroke or continuous reciprocation of the piston and knife attached thereto.

The reciprocating motion of the piston and knife will continue as long as there is pressure in the circuit and the foot pedal 41 remains depressed with valve 42 in the open position.

With the connection of lines 75 and 81 to conduits 24 and 26, as shown the piston within the operating cylinder will automatically retract when the foot of a user is removed from the foot pedal operating means 41. The piston will remain in this retracted position since pressurized fluid will be trapped in the hydraulic cylinder to act against one side of piston 78, while at the same time exhausting the other side of the operating cylinder.

If the connection of these lines 75 and 81 to the conduits are interchanged, the operating cylinder will automatically stop with the piston in the fully extended position when pressure is removed from the foot pedal operator.

The operating circuit is provided with the by-pass valve 37 for safety purposes. In the closed position, as shown by the position of switch 39 in FIG. 2, fluid pressure present in manifold 31, and line 33, can not pass through valve 37 to manifold 61. However, when bypass valve 37 is opened, by moving the switch 39 to the left as shown in FIG. 2, the pressurized fluid contained in valve 37 will be simultaneously delivered through line 93 to a right angle port 97 and line 95 to a shuttle or double check valve.

The pressurized fluid from the right angle port 97 is fed into a pilot actuator 99 to move the piston thereof in the direction toward three-way valve 47 to thereby close valve 47 and to block the flow of fluid from manifold 31 to line 45 and through valve 47.

At the same time, pressurized fluid from manifold 61 flows through line to shuttle or double check valve 55 and into three-way valve 57 to thereby operate the piston in pilot actuator 63. This moves the spool contained within spool ,valve 49 toward the pilot actuator 65 to redirect the flow of pressurized fluid through spool valve 49 from line 89 into line 67. Fluid pressure is then applied to piston 78 for movement of the rod 82 to the extended position.

As pointed out above, if lines 77 and 79 from the instrument to conduits 24 and 26 are interchanged, the instrument cylinder rod will be moved to the retracted position when by-pass valve 37 is manually opened.

With valve 37 in the open position, the piston of the operating cylinder can be locked in either the extended or retracted position depending on the connection of lines 77 and 79, and depression or retraction of the foot pedal will not operate the piston. This locking of the piston in position, provides a built-in safety feature which prevents the accidental movement of the instrument cylinder rod and blade during either insertion or withdrawal of the instrument should the foot pedal operator be inadvertantly depressed.

Turning now to FIG. 3 there shown is a preferred embodiment of the resectoscope of the present invention having the operating cylinder 80 attached to one end thereof. Conduits 77, 79 are shown connected thereto for attachment to conduits 24,26 for the application of fluid pressure from lines 75,81 for operation of piston 78. As shown, the preferred instrument comprises a wellknown Thompson resectoscope having a sheath 101 with a fenestra 103 formed therein. The rod 82 is connected (FIG. 5) to piston 78 and carries the cutting blade (not shown) within the sheath for resecting a portion of tissue forced into the fenestra 103. Therefore, upon reciprocation of the piston 78 within the operating cylinder 80 by the application and exhausting of fluid pressure to opposite sides thereof, the rod and blade will be automatically reciprocated.

FIG. 5 shows an improved embodiment of the Thompson resectoscope also having the piston 78 reciprocally mounted within the opeating cylinder 80. A sleeve 105 is secured to rod 82 and a pin 107 is fixed to the sleeve. The pin extends into. a spiral opening or slot 109 formed within a sleeve 111 held in the cylinder 80. In this manner, as the piston 78 is moved in either direction by the application of fluid presure thereto, the coaction of the pin 107 in the slot 109 will cause the rod 82 and its attached blade to rotate to further facilitate the cutting of tissue forced into the fenestra of the resectoscope.

As shown in FIG. 3, a base 113 is attached to the operating cylinder and is provided with the usual connections as well as the observation port concentric with hollow rod 82 now provided on Thompson resectoscopes. This observation can also be optically ground to suit the individual surgeons eye prescription.

The present invention is provided with additional safety features should the cutter engage a hard object, such as a stone or the like, contained within the prostatebeing resected. Normally, the cutting force applied by the movement of the piston will not be sufficient for the blade to pass through the hard object and the cylinder rod will not advance. The automatic action of the present invention allows the rod and cutting blade to stop, retract and continnuously engage the object to repeat the complete cutting cycle until the fluid pressure is increased sufficiently to allow the blade to pass through the object.

Throttle vlaves 69,85 are preferably adjustable needle valves to allow the fluid pressure within the circuit, and therefore the speed of reciprocation of the blade, to be regulated from essentially zero to that allowed with the maximum fluid pressure available from the pressure source.

It is therefore an important advantage of the present invention that an automatic, continuously operated resectoscope for resecting a prostrate gland or the like is provided. This resection may be accomplished by using only one hand to thereby free the other hand of the user.

Because of its automatic operation, the present invention requires fewer manipulations, smaller angular excursions and shorter sheath insertions because of the inherent increase in speed and cutting force available with the instrument. This also diminishes trauma to the normal surrounding tissues of a patient being operated on and appreciably reduces the time that the patient must be held under anesthesia.

A further advantage is provided by the safety features of the present invention whereby the cutting blade of the invention may rest within the retracted or extended position by release of the foot pedal operator or by the operation of the by-pass valve for permanently locking the cutting blade in the desired position.

And yet another advantage of the invention is the fact that all valves and fittings of the operating circuit are commercially available elements which can be easily assembled to achieve the foregoing advantages, and no special equipment need be manufactured or designed.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. it is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. A hydraulic actuator for use with a cold-punch resectoscope having an elongated sheath which is formed for insertion in the transurethral tract comprising an elongated assembly secured to said sheath and having a reciprocating piston mounted therein, said piston having a hollow cylindrical rod extending from one end thereof and carrying a resecting knife at the free end of said rod disposed internally of said sheath, said elongated assembly including a pair of inlet ports communicating internally of said assembly an opposite ends of said piston to enable said piston to be reciprocated, and manually controlled hydraulic operating circuit connected with said inlet ports for powered reciprocation of said piston and said resecting knife in said sheath, said hydraulic operating circuit being portable and wholly contained within a separate carrying case and having means for connection to said inlet ports of said assembly and to a separate pressurized fluid source.

2. The hydraulic actuator of claim 1 wherein said carrying case is provided with a liner of insulating material completely surrounding said operating circuit when said carrying case is closed to muffle the noise of said circuit during operation of said resectoscope.

3. The hydraulic actuator of claim 2 wherein said carrying case is in the form ofa brief case or the like having external connections mounted thereon to facilitate connection of said operating circuit between said resectoscope and said pressurized source of fluid.

4. The hydraulic actuator of claim 3 wherein said hydraulic operating circuit is comprised of a plurality of separate modular units secured together within said case.

5. The hydraulic actuator of claim 1 wherein said operating circuit includes a foot pedal operator connected to said source of pressurized fluid and said hydraulic circuit to permit said circuit and said resectoscope to be normally controlled by the foot of a user upon depression and release of said operator.

6. The hydraulic actuator of claim 1 including means connected between said elongated assembly and said piston for rotation of said piston and said knife during reciprocation thereof.

7. The hydraulic actuator of claim 6 wherein said rotation means comprises a spiral slot formed internally of said assembly, and

means engaged with said cylindrical rod and coacting with said slot whereby said resecting blade is caused to rotate as said means moves within said slot during reciprocation of said rod in said sheath.

8. A hydraulic actuator for use with a cold-punch resectoscope having an elongated sheath which is formed for insertion in the transurethral tract comprising an elongated operating handle assembly capable of being connected to said sheath,

a double ended piston mounted in said handle and capable of being recirpocated therein,

a hollow clindrical rod secured to one end of said piston, the other end of said rod disposed in said sheath and carrying a cutting blade at the free end thereof,

a pair of inlet ports formed in said handle assembly to allow pressurized fluid to be fed to opposite sides of said piston alternately to cause reciprocation of said piston and said blade with respect to said sheath,

a portable hydraulic operating means fluidly connectable to said parts and to a source of fluid pressure, and

a foot pedal operator connected to said operating means and to said source of fluid pressure to permit normal control of the speed of reciprocation of said piston and said cutting blade by the degree of depression and retraction of said foot pedal.

9. The hydraulic actuator of claim 8 including a spiral slot formed within said assembly,

a sleeve mounted on said rod, and

a pin fixed to said sleeve and coacting with said slot whereby, upon reciprocation of said piston and said rod within said assembly, said rod will be rotated as said pin moves within said slot.

10. The hydraulic actuator of claim 8 wherein said hydraulic operating means includes bypass means for locking the rod either fully retracted or fully extended, and

manually separately operable throttle control valves to vary the back pressure on the piston for controlling the speed of retraction and/or extension of the rod and knife in the sheath.

# ll i i 

1. A hydraulic actuator for use with a cold-punch resectoscope having an elongated sheath which is formed for insertion in the transurethral tract comprising an elongated assembly secured to said sheath and having a reciprocating piston mounted therein, said piston having a hollow cylindrical rod extending from one end thereof and carrying a resecting knife at the free end of said rod disposed internally of said sheath, said elongated assembly including a pair of inlet ports communicating internally of said assembly on opposite ends of said piston to enable said piston to be reciprocated, and a manually controlled hydraulic operating circuit connected with said inlet ports for powered reciprocation of said piston and said resecting knife in said sheath, said hydraulic operating circuit being portable and wholly contained within a separate carrying case and having means for connection to said inlet ports of said assembly and to a separate pressurized fluid source.
 2. The hydraulic actuator of claim 1 wherein said carrying case Is provided with a liner of insulating material completely surrounding said operating circuit when said carrying case is closed to muffle the noise of said circuit during operation of said resectoscope.
 3. The hydraulic actuator of claim 2 wherein said carrying case is in the form of a brief case or the like having external connections mounted thereon to facilitate connection of said operating circuit between said resectoscope and said pressurized source of fluid.
 4. The hydraulic actuator of claim 3 wherein said hydraulic operating circuit is comprised of a plurality of separate modular units secured together within said case.
 5. The hydraulic actuator of claim 1 wherein said operating circuit includes a foot pedal operator connected to said source of pressurized fluid and said hydraulic circuit to permit said circuit and said resectoscope to be normally controlled by the foot of a user upon depression and release of said operator.
 6. The hydraulic actuator of claim 1 including means connected between said elongated assembly and said piston for rotation of said piston and said knife during reciprocation thereof.
 7. The hydraulic actuator of claim 6 wherein said rotation means comprises a spiral slot formed internally of said assembly, and means engaged with said cylindrical rod and coacting with said slot whereby said resecting blade is caused to rotate as said means moves within said slot during reciprocation of said rod in said sheath.
 8. A hydraulic actuator for use with a cold-punch resectoscope having an elongated sheath which is formed for insertion in the transurethral tract comprising an elongated operating handle assembly capable of being connected to said sheath, a double ended piston mounted in said handle and capable of being reciprocated therein, a hollow cylindrical rod secured to one end of said piston, the other end of said rod disposed in said sheath and carrying a cutting blade at the free end thereof, a pair of inlet ports formed in said handle assembly to allow pressurized fluid to be fed to opposite sides of said piston alternately to cause reciprocation of said piston and said blade with respect to said sheath, a portable hydraulic operating means fluidly connectable to said parts and to a source of fluid pressure, and a foot pedal operator connected to said operating means and to said source of fluid pressure to permit normal control of the speed of reciprocation of said piston and said cutting blade by the degree of depression and retraction of said foot pedal.
 9. The hydraulic actuator of claim 8 including a spiral slot formed within said assembly, a sleeve mounted on said rod, and a pin fixed to said sleeve and coacting with said slot whereby, upon reciprocation of said piston and said rod within said assembly, said rod will be rotated as said pin moves within said slot.
 10. The hydraulic actuator of claim 8 wherein said hydraulic operating means includes bypass means for locking the rod either fully retracted or fully extended, and manually separately operable throttle control valves to vary the back pressure on the piston for controlling the speed of retraction and/or extension of the rod and knife in the sheath. 